Category Archives: Unix

SUDO

SUDO, or Super User Do, is a program that allows users to run other programs using another user’s security privileges. Companies that require a certain degree of security when running programs use this to grant security privileges to selected employees without compromising the system.

A password is required for each user. However, it can be reconfigured so that it will only ask for the root password or will not ask for any password at all. It is then able to log in each command, then run and perform every one. Some cases even allow SUDO to completely supplant the super user login for administrative tasks.

Brief History

Super User Do was first conceptualized and applied by Bob Coggechall and Cliff Spencer. It first ran on a VAX-11. An updated version was later posted in a forum on December 1985. It was meant to divide labor and allow a more fluid style of forwarding tasks to other people within the workplace. This has since been developed and improved into a more user-friendly version by Todd C. Miller.

Main Use

The main use of SUDO is to allow other people to access databases and deliver commands as the “Super User”. This means that the task or the workload is distributed, thinned and thus lightened for each individual within the sphere. As each command can be logged in, there is also an inherent check-and-balance scheme that allows superiors to check on what and where their employees have logged all through the time they were using the system.

SUDO Updated

Further updates led to the release of a fully functional and practical version used by different bureaus. In 1994, Todd Miller released a version with fixed bugs and support for more operating systems. It also allowed for more systems to be compatible with the program.

Todd then developed the program into something new and with lesser bugs. He removed the “SU” prefix in 1999 because there hasn’t been an official release of SUDO from the original authors. He then rewrote the SUDOers parser in 2005 to support the features that had been “taped” on to the program since 1996.

Linux File Server

The Linux File Server stores files in a central location while permitting access to networked computers. It differs from other file servers because it uses Linux as its base operating system.

Uses of the Linux File Server

Through a file server, users are able to save work and can access files without the burden of carrying disks. Access privileges can be limited to guests, members, and other registered users.

Linux-dedicated file servers permit networked computers to carefully share files. This also allows users to save different types of data and give them access to files through a software client.

A file server may allow all files to be stored in a central system and can accommodate centralized backup methods and even security practice systems. Individuals can also allot different permit rights to stored information.

What are the Benefits of the Linux File Server?

  1. Others can share files. A project file can easily be modified and shared by multiple users. The storage of these files in shared directories allows each user to work directly on the document.
  2. The network server’s files is protected and backed up regularly. If a file is accidentally deleted, it can be restored from the system. If the PC’s hard drive fails, the files that have been saved in the server will not affected.
  3. For multiple PCs, files in the server may be available on the different computers connected to the network. This means users can access files from any computer as long as it is connected to the network.

Advantages of the Linux File Server

  • Strong performance. Linux was made and designed to be a very strong operating system. Hardware resources that center on processing users recommend these.
  • Reliability. The Linux File Server can last for a long time.
  • Easy to use. Users have found rebooting and management to be very easy.

Cost of the Linux File Server

This can be purchased for as low as $1400. This includes the software and the default configuration.

How to Change a Solaris Hostname

In the Solaris operating system (OS), a complex process is required to change an installed server’s hostname. To change a hostname in Solaris, these following files should be edited:

  • /etc/hosts
  • This will show an IP address for the hostname. Modify the hostname at this file location to the host’s new name.

  • /etc/nodename
  • This is similar to Linux’s /etc/HOSTNAME. Modify the hostname in this location.

  • /etc/hostname.hme0
  • ‘hme0’ is the name of the interface, which can be retrieved from the ‘ifconfig’ command. Modify the hostname here.

  • /etc/net/tic*/hosts
  • Change all information here to align with all the data in the files mentioned above.

  • /etc/resolv.conf
  • Specify the domain resolution and DNS server information in this file location.

  • /etc/defaultrouter
  • Input the IP address of the Solaris host’s default router here.

    After editing the data at these file locations, go to the command prompt and type the hostname. Reboot the server and test the changes to ensure proper operation.

    A Unix-based OS, Solaris was launched by Sun Microsystems in 1992 to succeed SunOS.

    The Solaris OS is popular due to its scalability (a network, process, or system’s capability to handle increasing amounts of work), specifically in Scalable Process Architecture (SPARC) systems. Solaris also sustains servers and workstations based on SPARC and x86 (the most commercially widespread instruction set architecture in personal computing), which are from SunOS and other system vendors. Efforts are underway to support various other platforms.

    Solaris is certified through the Single Unix Specification. Originally created as proprietary software, it is now supported by systems from major server vendors. Most of the codebase (all source code used in building a particular component or application) is currently open-source software from the OpenSolaris program.

Change Shell

In computer language, a shell is a prompt where the user can type a specific command. After accepting the commands entered by the user, the shell passes them to the application that will perform the said commands.

Microsoft Windows is one of the most well-known operating systems that use a shell. Apart from the Windows shell, there are other types of shells created by certain companies. An example of this is Korn, which is a shell developed by AT&T.

Changing the shell consists of a few steps. If you have Windows as your operating system, you should first have a set of replacement shells aside from the one you are currently using. You can find these components in shell information sites such as Shell-Shocked.Org.

After you have found a replacement shell, you need to open Regedit. You can do this by clicking on the Start Menu, clicking on Run, and entering Regedit in the edit field of the Run dialog box. Once Regedit is loaded, go to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon. You need to find the option for the shell and change the shell from Explorer.Exe to the new one by indicating its full path. You can then save the changes and exit Regedit.

To see the newly loaded shell, you need to log out and log back in. If the new shell does not appear, repeat the above steps. If the new shell still does not appear, you can try using other shells present in shell information sites.

Unix Emulator

A Unix emulator is a software tool that presents a graphical interface and a set of functions that closely resemble those included in a full version of a Unix Operating System. This type of utility is developed so that individuals interested in Unix Operating Systems can learn about the said type of software.

A Unix emulator is usually installed in a computer with an existing Operating System. Once it has been set up, a Unix emulator will have the capability to make the existing Operating System behave like the Unix Operating System. To do this, a Unix emulator may make minor changes in the original OS of the computer.

Functions of a Unix Emulator

This type of emulator will make most if not all of the Unix commands available to the user. The emulator also displays the messages, terminals, and command lines that are common in a Unix Operating System. It has header files and libraries that allow the user to recompile and set up Unix applications. While running the emulator, the user can create files, execute commands, and open applications within a Unix environment. A Unix emulator can also enable the user to connect his computer to a network and access other machines through the emulator’s interface.

Some Unix emulators are only compatible with a specific Operating System. However, there are also Unix emulators that can run on various types of systems. Similar to other software tools installed in a computer, a Unix emulator can be closed and removed from the computer memory.

Unix emulators can be downloaded from certain websites. They are generally free software tools, although some need to be purchased.

For more information on Unix Emulator read:

  • Unix Emulator
  • Unix Emulator
  • Unix Download

    One of the unique characteristics of Unix based Operating Systems is that they are available for download on the World Wide Web. You can choose among several different versions of Unix download and acquire them from the Internet.

    To select the best option, you need to know the general features of each one. So to help you get started, here are several types of downloadable Unix Operating Systems:

    Solaris Operating System

    The Solaris Operating System is a well-known Unix download. Developed by Sun’s systems, Solaris Unix features innovative functions and advanced security. This Unix download is compatible with AMD Opteron, SPARC, and Intel Xeon-based systems. With its open source packages, dynamic tracing capabilities, and self-healing functions, this Operating System is highly recommended by companies and businesses.

    Fedora Linux

    Fedora Linux is another popular Unix download. This Operating System is the cornerstone project of the Linux community. It aims to provide users with a complete and general Operating System. The software components of Fedora Linux are free of charge and are built together in a public forum. Also, the team responsible for Fedora Linux encourages other developers to participate in the development of the project.

    OpenBSD Unix

    OpenBSD Unix is a multi-platform Operating System. Its notable qualities include portability, integrated cryptography, and proactive security. In addition, OpenBSD supports emulation of most programs from Solaris, BSD/OS, and SunOS.

    Ubuntu

    Ubuntu is an Operating System publicly developed by an online community. It presents the user with standard applications such as word processing software and email programs. It also has more advanced applications such as programming tools and Web server software.

    Additional Reading on UNIX Download

    Unix List Users

    The Unix system has several commands that enable the user to determine the other users of the system. These commands help keep track of individuals who use the system and their activities.

    The first set of commands lists down all users who are presently logged in. These commands can be used to identify the ones whom the user can work and interact with in the system.

    The “w” command shows the number of users and the load average in the system. This is useful for those who want to have as much detail about the other users as possible.

    The “who” command is a more concise version of the “w” command. The “who” command drops the column headers and shows data about the users only.

    The “users” command lists down only the names of users who are logged in.

    Apart from these, Unix also has commands for listing down all Unix users. These commands will even show the ones who are not logged in. Through the following set of commands, one can track the history of all users who have handled the Unix system for reference purposes.

    To list down all the users, one can enter the following command:

    “cat /etc/passwd”

    This command will access the system’s password file, which contains the information about all Unix users. The “cat /etc/passwd” command will list down the user names and real names of Unix users.

    Finally, to see only one field from the file, you can use the “cut” command. For example, this will show only the user names:

    cat /etc/passwd | cut -d: -f1

    Change Unix Password

    Using a Unix password ensures that your system and all your data are safe from unauthorized access. However, you may encounter security threats which may cause you to change your password. If faced with these threats, you need to learn how to change your Unix password.

    Steps to Change Unix Password

    1. Use the “passwd” command to change your Unix password. Once you enter the “passwd” on the command line, a set of fields will appear.
    2. Above the fields, this title will appear on your screen: “Changing local password for [user name]”, where [user name] contains your user name.
    3. Type your old password in the first field.
    4. Type your new password into the second field.
    5. Retype your new password into the third field.

    Make sure the new password you typed in the second field and the one you typed in the third field are exactly the same.

    Example

    Here is an example wherein a user named Sammy is changing his password.

    $ passwd

    Changing local password for Sammy

    Old Password:

    New Password:

    Retype New Password:

    Make sure that your new password is not closely related to any information about you. As a rule, your password should contain at least six characters. Ideally, you can have both letters and numbers in your new password.

    After you have changed your password, you can try logging in by typing it. If you think you might forget your new password, write it down where only you can find it.

    Unix Grep

    Unix grep is a search command built into a number of Unix Operating Systems. This command was built to make certain tasks simpler.

    Unix grep is a command utility whose main purpose is to search for lines matching a given regular expression. Once these lines are found, they will be printed. The user can access the Unix grep command through the command line or terminal from any location in the Unix Operating System.

    The Unix grep command becomes particularly useful when the user needs to search through more than one file. This is because Unix grep is capable of searching through any amount of text in order to find the information he is looking for. The lines containing the information will subsequently be displayed on the user’s screen. The user can then easily access the said search results.

    To further understand how the Unix grep search command works, here is an example of the said command:

    Grep test sample.txt

    The first part of the example is the actual command. The second word is the text the user would like to find. The third is the name of the file the user wants to search for all instances of the word “test”.

    Since the Unix grep command is inherently case sensitive, the word “Test” will not be seen on the screen, although it may be present in the file. However, by using the “-I” flag before the word the user wants to find, he will be able to deactivate the command’s case sensitive feature.

    Below is another example of the Unix grep command:

    Grep ‘^or’ sample.txt

    Putting a caret will find the “or” word as it appears by itself. This means that words such as “core” and “poor” will not be found and displayed.

    Umask

    Umask (User File Creation Mode Mask) refers to a function in POSIX (Portable Operating System Interface) environments. The Umask function involves the default file system mode for new files and directories of the current process.

    Umask determines the existing file permissions not set for any newly created file. This function is expressed in octal representations. The permissions of a particular file created under a Umask value are determined using a set of bitwise operations. These include bitwise AND and bitwise NOT. It should be noted that the changes will take effect only during the current session.

    In terms of full access, the value for files is 666, while the value for directories is 777. In most Unix shells, a specific Umask command affecting all processes being executed is present.

    Umask values can vary depending on the type of process being carried out. However, a few common Umask values are used in standard machines. One of these values is 022, which ensures that new files can only be modified by its creators. This prevents unauthorized individuals from accessing and editing the files in a particular work station.

    Another example of a common Umask value is 002. This provides the appropriate amount of permission for the enabled file group. Through this value, multiple users can simultaneously access a file. This is useful in shared work areas where two or more users work on the same file.